1. Field
Exemplary embodiments of the present invention relate to a differential amplifier circuit that amplifies a differential signal.
2. Description of the Related Art
Differential amplifier circuits amplify a voltage difference between input, signals to generate output signals. The differential amplifier circuits are used in most integrated circuit chips.
FIG. 1 is a diagram illustrating a conventional differential amplifier circuit.
Referring to FIG. 1, the differential amplifier circuit includes a differential amplification unit 110 and an enable transistor 120.
The differential amplification unit 110 amplifies a voltage difference between input signals IN and INB to generate output signals OUT and OUTB. When the input signal IN has a voltage that is higher than that of the input signal INB, the output signal OUT is generated with a logic high level and the output signal OUTB is generated with a logic low level. Furthermore, when the input signal NB has a voltage higher than that of the input signal IN, the output signal OUT is generated with a logic low level and the output signal OUTB is generated with a logic high level.
The enable transistor 120 allows a current to flow through the differential amplification unit 110 such that the differential amplification unit 110 is enabled when an enable signal EN is activated, and substantially prevents a current from flowing through the differential amplification unit 110 such that the differential amplification unit 110 is disabled when the enable signal EN is deactivated. A high amount of current is consumed in the operations of the differential amplification unit 110, but the enable transistor 120 disables the differential amplification unit 110 when the amplification operation of the differential amplification unit 110 is not required, so that it is possible to reduce unnecessary current consumption.
The enable transistor 120 substantially prevents unnecessary current consumption by enabling/disabling the differentia amplification unit 110, but the enable transistor 120 is serially coupled to elements in the differential amplification unit 110, so that current consumption of the differential amplification unit 110 may increase and the operation speed of the differential amplification unit 110 may be reduced by the enable transistor 120.